Aluminum chloride-catalyzed intramolecular allyl-migration reaction of allyl(chloromethyl)silanes and trapping of the intermediate with allyltrimethylsilane

Abstract

Allyl(chloromethyl)diorganosilanes [CH2=(CHCH2SiRR2)-R-1(CH2Cl), R' = Me, Ph; R-2 = Me, Ph, P-ClC6H4] in the presence of aluminum chloride undergo an allyl rearrangement reaction with allylic inversion to afford (3-butenyl)diorganochlorosilanes at room temperature. When allyltrimethylsilane was added to the reactions, the intermediate was trapped to give 1,1-dimethyl-3-(2-trimethylsilylmethyl-4-pentenyl)silacyclopentane (4) along with 3-(butenyl)-dimethylchlorosilane in 40% and 18% yields, respectively. The formation of 4 can be explained by the addition reaction of allyltrimethylsilane to 1-silacyclopent-3-yl cation produced by the intramolecular cyclization of (allyl)silylmethyl cation intermediate derived from the interaction of the chloromethyl group with aluminum chloride catalyst, followed by desilylation reaction.